1. Field of the Invention
The present invention relates generally to measuring the electrical characteristics of a material, and more particularly to measuring the resistivity or conductivity of materials which do not possess a defined geometry, such as powder samples.
2. State of the Art
Techniques for measuring the conductivity of a material are well known. Conductivity corresponds to the inverse of resistivity, and these two electrical characteristics can easily be correlated to one another.
Typically, the conductivity of a material is measured by contacting two probes (e.g., the probes of a conventional ohmmeter) to opposite ends of the material. A constant electrical current is passed via the two probes through the material. By measuring this current for a given voltage across the two probes, the resistance, and thus the conductivity, of the material can be determined.
The foregoing measurement technique is relatively accurate for detecting conductivity of solid materials having a relatively well defined geometry. However, such a measurement is relatively inaccurate for measuring the conductivity of materials which do not have well defined geometries, such as powders and other compressible materials. One reason for the inaccuracy of this measurement is an inability to establish reproducible contact between the probes and the material.
Accordingly, there is a need for an apparatus and method which can accurately detect electrical characteristics such as conductivity of materials which do not possess well defined geometries.